Pressure loaded pumps



June 16, 1964 c. P. DAHL 3, 7, 39

PRESSURE LOADED PUMPS Filed April 27, 1962 2 Sheets-Sheet 1 14a 21 3 .?0 Pi Ira/672157 Cari J .Dafil June 16, 1964 c. P. DAHL 3, 37, 39

PRESSURE LOADED PUMPS Filed April 27, 1962 2 Sheets-Sheet 2 jrzverzl or Carl j? .Dakl

United States Patent P E SURE LGADED PUNHS Carl P. Dani, Maple Heights, Qhio, assignor to Borg- Warner Corporation, Chicago, 111., a corporation of Illinois a Filed Apr. 27, 1962, Ser. No.190,6l6

3 Claims. (ill. 103- 426) This invention relates to improvements in pressure loaded pumps, more particularly to sealing means and a sealing arrangement in a pressure loaded pump to substantially isolate the inlet side from the outlet side thereof.

In the manufacture of small pressure loaded gear pumps, leakage around the pumping gear journal bearings from the outlet (high pressure) side and the pressure 7 comprisinginsents of resilient sealing material, preferably an elastomeric composition such as rubber, neoprene or similar material, fitted within grooves running along the peripheral surfaces of the pumping gear journal bearings. Various modifications and arrangements incorporating this basic principle are described and illustrated in this specification. 7

It is therefore an object of the present invention to provide an improved pressure loaded gear pump having increased efliciency resulting from the reduction of leakage from high pressure to low pressure areas.

Another object of the invention is to provide a pressure loaded gear pump having a novel sealingarrangement virtually isolating the inlet side from the outlet side of the pump. I

Other and more particular objects and advantages will be readily apparentirom the following detailed descrip tion and drawings wherein: a

FIGURE 1 is a cross-sectional View taken along the plane of line 11 of FIGURE 2, with certain portions broken away;

FIGURE 2 is a cross-sectional view taken along the plane of line 2-2 of FIGURE 1 with certain portions broken away;

FIGURE 3 is a cross-sectional view taken along the plane of line 3-3 of FIGURE 1; FIGURE 4 is a sideelevational view of a sub-assembly including the pumping gears and the journal bearings;

, 3,137,239 Patented June 16, 1964 against the pumping gear faces by a pressure proportional to the discharge, pressure of the pump. When the pump is operating at relatively low discharge pressures, the force against the pumping gear faces is relatively low; but as the discharge pressure increases, the loading on the pumping gear faces increases in direct proportion to the discharge pressure. e i 5 i As shown in FIGURES l and 2, the pump assembly A is adapted to be fitted within a conventional casing B, said casing having a fluid inlet opening 16 and, a fluid outlet opening 11. The casing per se forms nopart of the present invention and is merely shown to illustrate a typical installation of the pump assembly. i The pump assembly A comprises a housing including a body member 12 and a cover member 13 connected to said body member by any suitable means. The body member 12 is provided with a pair of axially extending, parallel, intersecting cylindrical bores 14a and 14b. Arranged within the bores are pumping gears 15a and 15b,

respectively intermeshing at the junoturelof said bores.

The upper pumping gear 15a is the drivinggear and. has integral, axially extending journals 16, 17 received in bearings 2i) and 21 respectively. Journal 16'is elongated and extends outof the body member 12 for connection to a suitable rotary drive means (not shown). The lower pumping gear 15b is the driven gear andincludes integral, axially extending hollow journals 18, 19 respectively received in bearings 22, 23. It will be noted that the upper and lower pairs of bearings are provided with opposed flat faces in contact with the sides of the pumping gears, said faces forming a pumping chamber there- FIGURE 5 is a isometric view of the sealing member FIGURE 8 is a detailed view along the plane of line s -s of FIGURE 7;

YFIGURE 9 is a view similar to that shown in FIG- URE 4 showing still another embodiment of the present invention;

FIGURE 10 is a view similar to that shown in FIG- URE 8 showing still another embodiment of the present invention; and p I I FIGURE 11 is a cross seotional view of a sub-assembly similar to that shown inFIGU-RE 9, of still another embodiment of the present invention.

The type of pump with which the present invention is concerned is known in the art as a pressure loaded pump.

between.

The body bearings 20, 22 adjacent the lefthand side of the body member are axially fixed with respectto said body member while the cover bearings 21, 23, so called because they extend into and are adjacent the cover, are axially movable with-respect tothe body member. 'The cover bearings also include motive surfaces in the form of pressure loadable faces 27a, 27b forming one wall of a fluid pressure chamber which communicates with fluid under high pressure, preferably pump discharge pressure, in a mannerto be described below. To prevent the bearings from skewing, conven tional pins 25 are provided in registered, blind openings in the respective pairs of bearings. i Y

The cover bearings 21, 23 include shank portions 21a,

23a (FIGURE 4) which are received in a pair of parallel bores 30, 31 in the cover member'13, said bores b'eing coaligned with the axes of the pumping gears. The

cover bearings are preloaded by springs 32, 33 which serve to force the cover bearings against sides of the pumping gears when the discharge pressure is low. Conventional 'O-ring seals 34a, 34b are positioned around the shank portion of the cover bearings.

As best shown in FIGURE 3, the bodymember is provided with fluid inlet passage means35 and L-shape'd outlet passage means 36 leading respectively to and from the pumping chamber .26. The cover member 13 includes a fluid passage means 37 registering with outlet passage 27b are subject to discharge pressure, and as explained To insure eiie'ctive' sealing, movable bearings are forced 7 above, this pressure increases the force against the sides of the pumping gears as the discharge pressure increases.

Lubrication of the system is provided by the inherent leakage of fluid along the sidefaces of the gears,'the

fluid flowing outwardly from the gears along said journals. Fluid at some pressure less than discharge pressure is thus passed in lubricating relationship with all portions of both journals. The fluid which is passed along journal 16 is discharged through U-shaped passage 43 into recessed area 44 to be finally discharged through the hollowed-out journals 18, 19. Small holes 45a, 45b are drilled in the cover bearings shanks 21a, 23a so that fluid is finally vented to inlet through the ports 46a and 46b in the cover member.

To prevent leakage from adjacent the discharge side of they pump and from the pressure loading chamber to the inlet side around the peripheral areas of the movable bearings, each said movable or cover bearing (FIG- URE 4) is provided with an axially extending slot or groove 41a, 41b adjacent the inlet side of the pump. The grooves have a generally rectangular cross section and extend from a point close to the pumping chamber defining face to the opposite edge of said bearings near the pressure loaded zone. Strips of sealing material 42 (FIGURE 5), preferably of rubber, neoprene, or similar elastomeric composition, are inserted into each groove and extend along the full length of each said groove. The thickness of the land portions separating each groove and sealing strip from the pumping chamber is on the order of .065 inch. It has been found that leakage through this relatively small space is negligible.

In most pumps, the inlet port overlaps the hearings to some extent. By placing the sealing means at an angle with respect to the longitudinal axis, the inlet port is partially surrounded on one side thereof to maintain a more eflicient seal. Accordingly, in the two modifications shown in FIGURE 6, and in FIGURES 7 and 8 the grooves, together with their respective sealing inserts, are arranged so that fluid leakage is prevented both from around the peripheral surface of the cover bearings and also from the high pressure chamber in back of the cover bearings. In both of these modifications, the sealing inserts have a generally bifurcated configuration so as to partially surround one side of the inlet port. As shown in FIGURE 6, grooves are formed in both the upper and the lower cover bearings and the inserts 42a, 42b constitute a sealing element having portions located at opposite sides of the line of intersection of the housing bores and spaced outwardly from the inlet port, and another portion adjacent to the line of intersection in the vicinity of the pressure chamber. In other words, the legs of the sealing member converge toward the back side of the cover bearings 27a and 27b.

In the other related modification shown in FIGURES 7 and 8, the sealing insert 50 is similarly arranged in a bifurcated configurationand comprises a single U- shaped member having a bight portion 59a and leg portions 50b parallel to the longitudinal axes of the bearings. This arrangement is effective in sealing all possible leakage paths from the pressure loaded bearings and is similar in principle to the angled configuration shown in FIGURE 6. 1

While the greatest leakage occurs around the cover bearings, in certain instances it has been found to be desirable to insure against leakage around the body bearings. Accordingly, in a modification shown in FIGURE 9, a corresponding pair of sealing means 42 is provided on the body bearings 20, 22. Should any fluid leak directly from the discharge' port down and around the body bearing flange, these bearing seals will efl'ectively control such leakage.

In another modification illustrated in FIGURE 10, the bottom of the groove 50 is formed in the shape of a V so that a longitudinally extending plenum chamber 51a is defined between the bottom of the insert 52 and the bottom of the groove. This plenum chamber 51a communicates directly with the pressure loaded area on the cover bear-ings so that the plenum chamber underneath the inserts is pressurized with fluid at substantially discharge pressure at all times. The sealing insert 52 thus acts as a piston in the groove, being urged by high pres sure against the bore surfaces to maintain positive sealing. An obvious variation of this basic arrangement could include, for example, a groove having a relatively flat bottom with a small V-shaped or half-round groove cut therein. It is only necessary that fluid pressure from the pressure loaded area be introduced underneath the insert along substantially the entire length thereof.

In still another modification shown in FIGURE 11, additional sealing means, 420-42h, have been provided around the periphery of the cover bearings, including some on the pressure side of the bearings. The latter have the effect of balancing the hearings in position and preventing misalignment with the body bearings and gears. It should be understood that additional sealing means may be provided on the body bearings also, the

precise location and number being largely a matter of 1 choice in design depending on pressures, materials, tolerances, etc.

From the foregoing description, it can be seen that the present invention provides an improved gear pump assembly having increased efliciency which can be attributed to the control and reduction of leakage from the discharge side of the pump to the inlet side thereof.

While the invention has been described in connection with certain specific embodmients thereof, it is to be understood that this is by way of illustration and not by limitation and that the scope of the invention is defined solely by the'appended claims which should be construed as broadly as consistent with the prior art.

It should be further understood that while the present invention has been described in connection with pressure loaded gear pumps, the sealing means could be employed in conventional gear pumps which do not include a pressure loading system. Moreover, while the most practical sealing system includes the sealing strips in the pumping gear journal bearings, this is by no means the only way to effect a seal of the type contemplated. The strips, for example, could be inserted into grooves in the housing bores in some of the modifications described with substantially the same results.

What is claimed is:

1. A gear pump comprising:

a housing provided with a pair of parallel, intersecting bores;

first and second bearing means received within said bores,

said first bearing means including a peripheral surface having the general configuration of a figure-eight closely fitted within said bores,

said second bearing means being spaced from and axially slidable with respect to said first bearing means and including a peripheral surface having the general configuration of a figure-eight fitted within said bores,

each said bearing means having a flat side wall facing the flat side wall of the other bearing means and cooperating with the housing bores to define a pumping chamber;

a pair of intermeshing pumping gears received Within said pumping chamber, each said pumping gear being journalled for rotation by said first and second hearing means;

fluid inlet means communicating with said pumping chamber adjacent the intersection of said bores on one side of said housing;

fluid outlet means communicating with saidpumping chamber adjacent the intersection of said bores on the other side of said housing;

a fluid pressure chamber at least partially defined by the back side of said second bearing means whereby said second bearing means is urged into engagement with one side of said pumping gears; and

elastomeric sealing means disposed between the peripheral surface of said second bearing means and said bore on the inlet side thereof,

said sealing means having a bifurcated configuration and including portions on opposite sides of the line of intersection of said bores and spaced radially outwardly from said inlet means,

said sealing means extending toward said fluid pressure chamber and including another portion disposed adjacent to said line of intersection in the vicinity of said fluid pressure chamber.

2. A gear pump as defined in claim 1 wherein said sealing means includes leg portions converging toward said fluid pressure chamber.

3. A gear pump as defined in claim 1 wherein said sealing means comprises a U-shaped member having leg portions extending generally parallel to the axis of said pumping gears on opposite sides of the line of intersection of saidintersecting bores and an integral bight portion extending parallel to said pumping chamber and joining said leg portions in the vicinity of said fluid pressure chamber.

References Cited in the file of this patent UNITED STATES PATENTS 

1. A GEAR PUMP COMPRISING: A HOUSING PROVIDED WITH A PAIR OF PARALLEL, INTERSECTING BORES; FIRST AND SECOND BEARING MEANS RECEIVED WITHIN SAID BORES, SAID FIRST BEARING MEANS INCLUDING A PERIPHERAL SURFACE HAVING THE GENERAL CONFIGURATION OF A FIGURE-EIGHT CLOSELY FITTED WITHIN SAID BORES, SAID SECOND BEARING MEANS BEING SPACED FROM AND AXIALLY SLIDABLE WITH RESPECT TO SAID FIRST BEARING MEANS AND INCLUDING A PERIPHERAL SURFACE HAVING THE GENERAL CONFIGURATION OF A FIGURE-EIGHT FITTED WITHIN SAID BORES, EACH SAID BEARING MEANS HAVING A FLAT SIDE WALL FACING THE FLAT SIDE WALL OF THE OTHER BEARING MEANS AND COOPERATING WITH THE HOUSING BORES TO DEFINE A PUMPING CHAMBER; A PAIR OF INTERMESHING PUMPING GEARS RECEIVED WITHIN SAID PUMPING CHAMBER, EACH SAID PUMPING GEAR BEING JOURNALLED FOR ROTATION BY SAID FIRST AND SECOND BEARING MEANS; FLUID INLET MEANS COMMUNICATING WITH SAID PUMPING CHAMBER ADJACENT THE INTERSECTION OF SAID BORES ON ONE SIDE OF SAID HOUSING; FLUID OUTLET MEANS COMMUNICATING WITH SAID PUMPING CHAMBER ADJACENT THE INTERSECTION OF SAID BORES ON THE OTHER SIDE OF SAID HOUSING; A FLUID PRESSURE CHAMBER AT LEAST PARTIALLY DEFINED BY THE BACK SIDE OF SAID SECOND BEARING MEANS WHEREBY SAID SECOND BEARING MEANS IS URGED INTO ENGAGEMENT WITH ONE SIDE OF SAID PUMPING GEARS; AND ELASTOMERIC SEALING MEANS DISPOSED BETWEEN THE PERIPHERAL SURFACE OF SAID SECOND BEARING MEANS AND SAID BORE ON THE INLET SIDE THEREOF, SAID SEALING MEANS HAVING A BIFURCATED CONFIGURATION AND INCLUDING PORTIONS ON OPPOSITE SIDES OF THE LINE OF INTERSECTION OF SAID BORES AND SPACED RADIALLY OUTWARDLY FROM SAID INLET MEANS, SAID SEALING MEANS EXTENDING TOWARD SAID FLUID PRESSURE CHAMBER AND INCLUDING ANOTHER PORTION DISPOSED ADJACENT TO SAID LINE OF INTERSECTION IN THE VICINITY OF SAID FLUID PRESSURE CHAMBER. 